A nautical autopilot (often nicknamed "Iron Mike") is an electronic, closed-loop steering system that automatically maintains a vessel’s course using input from a compass, GPS, or wind sensor. By controlling the rudder, it reduces operator workload and fatigue, ensuring efficient steering without continuous manual helmsmanship.

Core Components and Function:
Sensor Input: Gathers data from a compass (for heading), GPS (for routing), or windvane.

Computer: Calculates the required rudder corrections to maintain the desired course.

Drive Unit: A hydraulic pump or electric motor (tiller or wheel pilot) that physically moves the rudder.

Key Details:
Not a Replacement for Crew: It does not replace the need for a human to watch for traffic, avoid hazards, or manage navigation decisions.

Types: Primarily classified into wheel pilots for larger vessels and tiller pilots for smaller sailboats.

Operation: In addition to holding a straight compass heading, modern units can follow GPS waypoints or maintain a specific angle to the wind.

Autopilots are often mistaken for "self-steering gear," which technically refers to non-electric steering mechanisms (such as windvane systems) that don't rely on battery power.